There are no numbers given, just a question of relation.
A box with mass m rest on a board. One side of the board lifts up until the box begins to slide. For this to happen, the angle theta that the board makes with the horizontal floor depends on:
Fnet = -muN + mg
The Attempt at a Solution
I tried solving it in terms of the x component of W=mg.
So F=mg-f (f = muN or friction)
F=Wx - f
Those were my best attempts to come up with some sort of equation for this.